What I meant by different feeding methods was: different prey items of suitable sizes (mice and rats), offering different times of day, offering on tongs vs leaving the prey, different defrosting methods if trying F/T, trying F/T Or pre-killed or live, braining, etc...
As long as husbandry is solid and all other methods have been exhausted and the animal is unable to maintain a healthy weight then assisting is all you can do...